EChO Payload electronics architecture and SW design

EChO is a three-modules (VNIR, SWIR, MWIR), highly integrated spectrometer, covering the wavelength range from 0.55 $\mu$m, to 11.0 $\mu$m. The baseline design includes the goal wavelength extension to 0.4 $\mu$m while an optional LWIR module extends the range to the goal wavelength of 16.0 $\mu$m. An Instrument Control Unit (ICU) is foreseen as the main electronic subsystem interfacing the spacecraft and collecting data from all the payload spectrometers modules. ICU is in charge of two main tasks: the overall payload control (Instrument Control Function) and the housekeepings and scientific data digital processing (Data Processing Function), including the lossless compression prior to store the science data to the Solid State Mass Memory of the Spacecraft. These two main tasks are accomplished thanks to the Payload On Board Software (P-OBSW) running on the ICU CPUs.Comment: Experimental Astronomy - EChO Special Issue 201

New Measurement of the Relative Scintillation Efficiency of Xenon Nuclear Recoils Below 10 keV

Liquid xenon is an important detection medium in direct dark matter experiments, which search for low-energy nuclear recoils produced by the elastic scattering of WIMPs with quarks. The two existing measurements of the relative scintillation efficiency of nuclear recoils below 20 keV lead to inconsistent extrapolations at lower energies. This results in a different energy scale and thus sensitivity reach of liquid xenon dark matter detectors. We report a new measurement of the relative scintillation efficiency below 10 keV performed with a liquid xenon scintillation detector, optimized for maximum light collection. Greater than 95% of the interior surface of this detector was instrumented with photomultiplier tubes, giving a scintillation yield of 19.6 photoelectrons/keV electron equivalent for 122 keV gamma rays. We find that the relative scintillation efficiency for nuclear recoils of 5 keV is 0.14, staying constant around this value up to 10 keV. For higher energy recoils we measure a value around 20%, consistent with previously reported data. In light of this new measurement, the XENON10 experiment's results on spin-independent WIMP-nucleon cross section, which were calculated assuming a constant 0.19 relative scintillation efficiency, change from $8.8\times10^{-44}$ cm$^2$ to $9.9\times10^{-44}$ cm$^2$ for WIMPs of mass 100 GeV/c$^2$, and from $4.4\times10^{-44}$ cm$^2$ to $5.6\times10^{-44}$ cm$^2$ for WIMPs of mass 30 GeV/c$^2$.Comment: 8 pages, 8 figure

The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed by Herschel. I. Evidence of clumps, multiple arcs, and a linear bar-like structure

Context. The interaction between stellar winds and the interstellar medium (ISM) can create complex bow shocks. The photometers on board the Herschel Space Observatory are ideally suited to studying the morphologies of these bow shocks. Aims. We aim to study the circumstellar environment and wind-ISM interaction of the nearest red supergiant, Betelgeuse. Methods. Herschel PACS images at 70, 100, and 160 micron and SPIRE images at 250, 350, and 500 micron were obtained by scanning the region around Betelgeuse. These data were complemented with ultraviolet GALEX data, near-infrared WISE data, and radio 21 cm GALFA-HI data. The observational properties of the bow shock structure were deduced from the data and compared with hydrodynamical simulations. Results. The infrared Herschel images of the environment around Betelgeuse are spectacular, showing the occurrence of multiple arcs at 6-7 arcmin from the central target and the presence of a linear bar at 9 arcmin. Remarkably, no large-scale instabilities are seen in the outer arcs and linear bar. The dust temperature in the outer arcs varies between 40 and 140 K, with the linear bar having the same colour temperature as the arcs. The inner envelope shows clear evidence of a non-homogeneous clumpy structure (beyond 15 arcsec), probably related to the giant convection cells of the outer atmosphere. The non-homogeneous distribution of the material even persists until the collision with the ISM. A strong variation in brightness of the inner clumps at a radius of 2 arcmin suggests a drastic change in mean gas and dust density some 32 000 yr ago. Using hydrodynamical simulations, we try to explain the observed morphology of the bow shock around Betelgeuse. Conclusions: [abbreviated]Comment: 26 page

Influence of blade aerodynamic model on the prediction of helicopter high-frequency airloads

Brown’s vorticity transport model has been used to investigate the influence of the blade aerodynamic model on the accuracy with which the high-frequency airloads associated with helicopter blade–vortex interactions can be predicted. The model yields an accurate representation of the wake structure yet allows significant flexibility in the way that the blade loading can be represented. A simple lifting-line model and a somewhat more sophisticated liftingchord model, based on unsteady thin aerofoil theory, are compared. A marked improvement in the accuracy of the predicted high-frequency airloads of the higher harmonic control aeroacoustic rotor is obtained when the liftingchord model is used instead of the lifting-line approach, and the quality of the prediction is affected less by the computational resolution of the wake. The lifting-line model overpredicts the amplitude of the lift response to blade–vortex interactions as the computational grid is refined, exposing the fundamental deficiencies in this approach when modeling the aerodynamic response of the blade to interactions with vortices that are much smaller than its chord. The airloads that are predicted using the lifting-chord model are relatively insensitive to the resolution of the computation, and there are fundamental reasons to believe that properly converged numerical solutions may be attainable using this approach

Numerical study of web crippling strength in cold-formed austenitic stainless steel lipped channels with web openings subjected to interior-two-flange loading

In cold-formed stainless steel lipped channel-sections, use of web openings for service purposes are becoming increasingly popular. Web openings, however, result in the sections becoming more susceptible to web crippling. This paper presents a finite element investigation into the web crippling strength of cold-formed austenitic stainless steel lipped channel-sections with circular web openings under the interior-two-flange (ITF) loading condition. The cases of web openings located centred and offset to the bearing plates are considered in this study. In order to take into account the influence of the circular web openings, a parametric study involving 740 non-linear elasto-plastic finite element analyses was performed, covering austenitic EN1.4404 stainless steel grade. From the results of the parametric study, the effect of the size of the web opening, length of bearing plate and location of the web opening is investigated. Strength reduction factor equations are then proposed, that can be used to take into account such web openings in design

Operational quasiprobabilities for qudits

We propose an operational quasiprobability function for qudits, enabling a comparison between quantum and hidden-variable theories. We show that the quasiprobability function becomes positive semidefinite if consecutive measurement results are described by a hidden-variable model with locality and noninvasive measurability assumed. Otherwise, it is negative valued. The negativity depends on the observables to be measured as well as a given state, as the quasiprobability function is operationally defined. We also propose a marginal quasiprobability function and show that it plays the role of an entanglement witness for two qudits. In addition, we discuss an optical experiment of a polarization qubit to demonstrate its nonclassicality in terms of the quasiprobability function.Comment: 10 pages, 4 figures, journal versio

Higher derivative theories with constraints : Exorcising Ostrogradski's Ghost

We prove that the linear instability in a non-degenerate higher derivative theory, the Ostrogradski instability, can only be removed by the addition of constraints if the original theory's phase space is reduced.Comment: 17 pages, no figures, version published in JCA

Core-Clickable PEG-Branch-Azide Bivalent-Bottle-Brush Polymers by ROMP: Grafting-Through and Clicking-To

The combination of highly efficient polymerizations with modular "click" coupling reactions has enabled the synthesis of a wide variety of novel nanoscopic tructures. Here we demonstrate the facile synthesis of a new class of clickable, branched nanostructures, polyethylene glycol (PEG)-branch-azide bivalent-brush polymers, facilitated by "graft-through" ring-opening metathesis polymerization of a branched norbornene-PEG-chloride macromonomer followed by halide-azide exchange. The resulting bivalent-brush polymers possess azide groups at the core near a polynorbornene backbone with PEG chains extended into solution; the structure resembles a unimolecular micelle. We demonstrate copper-catalyzed azide-alkre cycloaddition (CuAAC) "click-to" coupling of a photocleavable doxorubicin (DOX)-alkyne derivative to the azide core. The CuAAC coupling was quantitative across a wide range of nanoscopic sizes (similar to 6-similar to 50 nrn); UV photolysis of the resulting DOX-loaded materials yielded free DOX that was therapeutically effective against human cancer cells